FAQ: 30 pin Extension Cable Recommendations

[RoadRanger]

Awesome job, Kevin!

[WK154]

Great job on finding the cause Kevin but now it would be greater if there was a solution other than 90 - 100% charge of the iPad. Anyone?

[soundog]

I was surprised this topic didn't come up much when I did a search, so was glad to find this info. I am replying to this old thread with new info based on experimentation.

I experimented with a 4-foot extension, and successfully decoupled the Mackie (noisy?) charging power from the data wires (clipped the black wire/pin 16 and red wire/pin 24) from the iPad end of the extension (after opening up the housing). These are the +5V and Gnd connections for charging. This resulted in reliable data "connection" to the Mackie but, of course, the iPad power drained over time.

So, I took an old USB cable and cut off the square connector end (leaving the flat rectangular end), and soldered the red and black wires to the same colored wires I had cut (connect to the iPad end). I cut a hole in the housing to accomodate the wires. Then, the extension cable and USB cable were taped together.

I use a regular iPad USB charger to connect to the USB cable, and the female end of the extension connects normally to the Mackie DL. The result: the Mackie does its data thing (mixing, recording, playing iPad audio, etc), while the cable is free of any charging noise. Charging is provided independently to the iPad via the USB cable.

I'm not responsible from any bad stuff happening...don't try this at home unless you are comfortable doing this sort of hacking. 

[WK154]

I had intended to get to this some time ago but... I'm glad someone else has. This points to the Mackie internal cable also being a problem since docked iPads still disconnect (no cable but internal ones). I trust that you no longer have ANY sync problems? It could also mean that the 5V power supply in the DL can't handle the full charging current of the iPad. I still have a cable that has more connections than used by the DL and it simply refuses to sync. One of these days I might get to removing the unused wires and find out which upset the iPad sufficiently to prevent sync. One note on cutting ground, you have removed the path to ground through the DL, which by the way was through a 160 ohm resistor. It is unclear what long term effect this might have if any since you are providing ground through the charger. No schematics make this trial and error. Hooking ground back up may be an interesting test. I always thought that this was too high a value and was tempted to reduce the resistor to a 51 ohm. Charging the iPad is a rather complicated affair since it also uses the data lines for status. The DL may not comply with the protocol as the Apple charger does. Measuring the charging and ground currents was also on my list.
Welcome soundog to this forum.

[soundog]

Interesting info on the ground resistor. I am learning the charging on an iPad (a 3 in my case) is complex, so I have been reading up on it as much as possible. As I spend more time with this custom cable, I am learning the charging is not reliable through any 5V USB supplies I have tried (I sometimes get a "not charging" message.) That includes Apple and other versions, of varying wattages and mA.

However, regardless of whether power is supplied or not, I have successfully left the extension cable (a 3-foot version I got off of Amazon for $6 that advertised audio and video support) connected and had no sync problems after hours of connectivity, even draining the battery from 100% to 65%. Encouraging, if only I can get reliable charging power.

Lets trade notes as we go ... I would love to come up with a stable cabling setup that keeps the iPad powered up and supports all of the wired DL features. Its challenging without schematics, and treading cautiously cause I don't want to damage any equipment in the process.

[WK154]

Will do. The reason for erratically charging is because you did not hook up the +/- USB data lines to the iPad from the Apple charger. This would of course conflict with the DL data lines to the iPad which may not follow the spec. A word of caution on the Li batteries they need close control or you may end up with a fire. I'm tied up for the next two weeks so I can't devote time to this (it's called retirement) .

[soundog]

I retired a couple of years ago, so now have time to mess with this sort of stuff. Its the best!!

I see your point on having the USB data lines connected! I want no fires, smoke, or explosions. 

So, for my "dual" decoupled USB charging cable + DL control data cable experiment: do you think if I connected the USB data lines (pin 25 and 27) on the cable at the iPad end only (so I would have all 4 USB connections on the USB charging cable like normal) that this might work? I am not certain which lines the DL is using to charge the iPad, but am assuming it would be 16, 23, 25, and 27. OR ... is the Mackie using 25 and 27 for sync/control data?

One question becomes how to treat any ground connections from the Mackie. Currently I have the pin 16 disconnected from the Mackie, and communication seems to be working with no loss of sync.

This dual cable hack is a fairly dramatic solution for the problem. A better solution would be to simply fix the source of the problem in the Mackie circuit, but who knows what the issue really is?? I realize that an extension cable is beyond intended usage, but I've used an extension with other iPad audio interfaces and had no issues.

[WK154]

I looked at this over a year ago and AFAIK the data lines are at a certain voltage for charging levels they apparently don't interfere with communications or maybe they do. I think that you can't do both at the same time, then again I maybe thinking about USB protocol. Need to revisit the subject. I hate Apple with their "intelligent cable BS".

[walterw]

all i can say is the 2' cablejive has been working nicely for me for a while now; i make sure my ipad 3 is at 100% before the night begins, and it stays connected (and at 100% charge) til the end of the  night.

i also make a habit of shutting the ipad off between sets to let it cool and recharge.  i shut it down straight from master fader, and it comes back straight to master fader without losing the sync.

[WK154]

Soundog you may want to look at this  http://cacophony.aspinock.com/index.php?topic=464.msg3462#msg3462

[soundog]

Thanks WK, that's helpful as I haven't opened my DL. The connections are similar to those in a camera connection kit.

I'm assuming all the GNDs you mention on the DL connector side are tied (common)?

The problem with extension cables dropping sync is still a mystery. Based on what I've seen so far, I may try another experiment in which i isolate/shield the power lines (3.3 and 5V) from all other lines (but keep all connections between the DL and iPad the same) to see if the cause is some sort of interference/capacitance problem. If not, it may be increased resistance in the length of the lines, and changing the resistor size on the DL end may be a cure.

[WK154]

Grounds all common on the DL side before 160 ohm resistor. Internal cable shield also tied to common. Where would you tie the shield drain from the power lines to?

[ijpengelly]

I bought a 2ft 30 pin extension from ebay and not surprisingly I was a bit disappointed when it didn't work for more than 15 seconds... not that disappointed since it was really cheap. However, after reading this I did a quick experiment yesterday and when the iPad is fully charged it holds the sync reliably and reconnects when required (after iPad has dropped into standby). Great find by Kevin. For my purposes it sounds like cutting the power cables within the extension would be the best strategy, which would mean I can fit a nice protective case and still be able to go to hard wired when I have wireless issues (thankfully not that often).

Now, Mackie... sort out your charging circuit!!!

[WK154]

Soundog more on this here:  http://cacophony.aspinock.com/index.php?topic=498.msg7231#msg7231

[soundog]

thx wk .... i just read the thread, and will continue to follow it to see if any hackpatch is discovered. for now i am using a 3 foot extension with the 5V power line severed, ipad 3 fully charged before a gig. this is working OK, but i wish there was a firmware fix available from Mackie. you listening, Mackie?